Conventionally a sample processing system provided with a plurality of sample processing apparatuses such as a multichannel blood cell analyzer or a blood smear sample preparing apparatus is known. The sample processing system transports a sample supplied by a user to these sample processing apparatuses and collects the sample already processed by the sample processing apparatuses.
Japanese Laid-Open Patent Publication No. 2001-74754 discloses an automatic analyzer provided with a rack setting unit where a rack holding a sample container is set, a sample feed transport line, a rack supply/collection unit which supplies the rack set in the rack setting unit to the sample feed transport line, a sample return transport line, a rack storage unit, and a plurality of analysis units. The automatic analyzer transports the rack supplied by the rack supply/collection unit in a feed direction using the sample feed transport line to analyze a target sample by any selected one of the plurality of analysis units. The post-analysis rack is transported in a return direction opposite to the feed direction by the sample return transport line and collected by the rack supply/collection unit, and then transported to and stored in the rack storage unit. The automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. 2001-74754 is structurally advantageous in that the rack setting unit and the rack storage unit are provided on the same side apart from the analysis units. This structure allows the user to supply (load) and collect the sample in one place.
Japanese Laid-Open Patent Publication No. H06-148202 discloses an automatic analyzer which has a sample supply unit where a sample rack is set, a transport line used to transport the sample rack supplied at a predetermined transport start position by the sample supply unit, a reaction unit which suctions a given volume of the sample from a sample container held in the sample rack transported to a predetermined suctioning position to perform a predefined test to the suctioned sample, return lines used to return the sample rack from which the samples are already suctioned, a sorting mechanism which sorts the sample rack to one of the return lines, a return mechanism which returns the sample rack returned by the return line selectively to the transport start position, and a rack storage unit which stores therein the test-completed sample rack. In the automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. H06-148202, the sample supply unit and the rack storage unit are provided on the same side apart from the reaction unit, and the sample rack to be retested is transported again to the transport start position by the return mechanism, whereas the sample racks which are not to be tested are transported to the rack storage unit.
In the automatic analyzer disclosed in the Japanese Laid-Open Patent Publication No. 2001-74754, if the sample held in the rack supplied from the rack supply/collection unit is analyzed by at least two analysis units, the sample is suctioned at the sample suctioning position in one of the analysis units to be analyzed there, and then further transported to the sample suctioning position of the other analysis unit to be suctioned and analyzed there. However, no regard is given to retesting (reanalysis) in the automatic analyzer.
In the automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. H06-148202, the sample rack holding the sample to be retested is transported to the exit of the transport line similarly to the sample rack which holds only the samples which need not be retested, and then transported by the return line in a direction opposite to the transport direction of the transport line back to the transport start position again. Thus, the sample rack has to travel a long transport path, which is a bottleneck in improving the efficiency of retest. In the case where a sample is currently suctioned from any other sample rack by the reaction unit on the downstream side of the transport direction, for example, it is necessary to suspend the transport of the sample rack to be retested until the suctioning is over, which causes clogging on the transport path. Whenever the traffic on the transport path is thus clogged, the retesting efficiency is significantly deteriorated.